A Bronx man under arrest on a gun charge walked out of a station house yesterday – the 21st prisoner to escape cops this year, authorities said.

The suspect, Omar A. Alihayphe, 26, escaped at about 12:15 p.m. and remained on the lam for about two hours until cops spotted him in front of 2085 Morris Ave., a few blocks from the 41st Precinct station house on Longwood Avenue in the South Bronx.

Police could not immediately explain how Alihayphe fled the station house.

But one officer, Edward Velazquez, was suspended without pay in the incident last night. Velazquez was assigned to watch the prisoner, officials said.

A spate of recent escapes has embarrassed law-enforcement officials.

“There is no excuse for officers who are careless,” Police Commissioner Ray Kelly said last month.

The escapees include a Brooklyn woman busted on a prostitution charge, an assault suspect in The Bronx and a drug suspect who sneaked out of a Manhattan courthouse. All were recaptured.